code: def check_if_parallel(dx1, dy1, dx2, dy2, tolerance=1.0e-5):
      """
      Check if two lines are parallel.
  
      Parameters
      ----------
      dx1, dy1, dx2, dy2 : float
          The gradients *dy*/*dx* of the two lines.
      tolerance : float
          The angular tolerance in radians up to which the lines are considered
          parallel.
  
      Returns
      -------
      is_parallel
          - 1 if two lines are parallel in same direction.
          - -1 if two lines are parallel in opposite direction.
          - False otherwise.
      """
      theta1 = np.arctan2(dx1, dy1)
      theta2 = np.arctan2(dx2, dy2)
      dtheta = abs(theta1 - theta2)
      if dtheta < tolerance:
          return 1
      elif abs(dtheta - np.pi) < tolerance:
          return -1
      else:
          return False
  
imports: from functools import lru_cache
  import math
  import warnings
  import numpy
  from matplotlib import _api
label_desc: Use image node_id 11 for calling a global function with example usage: check_if_parallel(dx1, dy1, dx2, dy2, tolerance) and returns: int, unknown, False